1. Technical Field
The invention relates generally to underground boring machines and, more particularly, to a control system for controlling the path of a drillhead of an underground-boring machine. Specifically, the invention relates to a control system that controls the horizontal and vertical direction of a drillhead of an Ago underground boring machine as the drillhead is advanced in a translational direction through a subterranean location.
2. Background Information
Underground boring machines are typically employed to install subterranean piping without the need for excavation, as well as for other purposes. When installing subterranean piping, the underground boring machine typically includes a sled which is driven along a track. The sled carries a pipe and includes a translation mechanism that engages the track and drives the sled forward. The sled also includes a rotation mechanism that operates a drillhead in front of the pipe. A rotating auger is typically disposed within the pipe, with the rotating auger drawing soil and rock away from the drillhead for discharge outside of the subterranean location. The pipe is incrementally driven in the translational direction until it is installed through the desired subterranean location.
As is generally known and understood in the relevant art, the pipe that is driven by the underground boring machine is made up of a plurality of shorter sections of pipe of a given length. During the drilling operation for a given section of pipe, the sled travels along the track in the translational direction, thus driving the pipe into the subterranean location. Once the sled has reached the end of the track, the pipe is detached from the sled and the sled is returned to its starting point at the opposite end of the track. A new section of pipe is then welded to the previous section of pipe and the sled is restarted. The sled thus incrementally drives each section of pipe until the collective length of pipe has been driven into the desired subterranean location.
In driving a subterranean pipe, it is desirable that the direction of the drillhead be controlled to ensure that the pipe that follows directly behind the drillhead is installed into the proper subterranean location. Without some level of control of the drillhead direction, the pipe could ultimately follow an uncertain path inasmuch as the varying densities of the soil and the presence of rocks can alter the direction of the drillhead in unpredictable ways. It is thus preferred to provide directional control over the drillhead.
It is also preferred that the specific subterranean location of the drillhead be determinable at various times in order to help provide meaningful control of the drillhead. Stated otherwise, the course of the drillhead can be properly corrected only after the precise location of the drillhead has been determined. Once the drillhead has been determined to be off the desired course, a course compensation can be provided in any of a variety of known ways to preferably return the drillhead to the desired course. Such course correction is not, however, without difficulty.
The course of the drillhead is preferably corrected on a frequent basis inasmuch as subterranean conditions can alter the course of the drillhead at virtually any time. Such monitoring often requires substantial concentration and effort by the operator, thus increasing labor costs. Once the drillhead has strayed off the desired course, the drillhead can be returned to the desired course only gradually inasmuch as the pipe typically has a limited capacity for bending. As is understood in the relevant art, the pipe follows the drillhead both through the deviation from the desired course and through the course correction, thus limiting the rate of course correction to correspond with the capacity of the pipe for bending as it follows through the subterranean course. It is preferred, therefore, that deviations by the drillhead from the desired course be immediately detected and corrected. Furthermore, it is desired that such deviations be corrected in the proper measure without the overcorrection that often results in the drillhead overshooting the desired path, thus requiring an additional correction to compensate for the improper excessive previous adjustment which resulted in the overcorrection.
In order to determine the location of the drillhead in the subterranean location, a positional transmitter or sonde is provided at the drillhead location, with the sonde often being installed inside the drillhead. The sonde produces a positional signal in the form of a generally dipole magnetic field that can be detected by a positional receiver.
Once the location of the drillhead has been determined, the direction of the drillhead can be altered in both the vertical and horizontal directions. Numerous methods exist for altering the direction of the drillhead, such as adjustment of control rods attached to the drillhead, adjustment of the cutting tools on the drillhead, as well as other methods. It is preferred, however, that the positional signal received by the positional receiver be used to directly control the direction of the drillhead without any corrective commands being required from an operator. It is desired that the receiver be selectively positionable above the grade at the desired terminus for the pipe. It is further desired that the receiver be movable from location to location to permit the pipe to be directed around obstacles and to permit the pipe to follow a desired course. It is also desired to provide a control system that controls both the horizontal and vertical direction of the drillhead as the pipe is driven in a translational direction below grade.
In view of the foregoing, an objective of the present invention is to provide a control system for an underground boring machine that controls the horizontal and vertical directions of the drillhead.
Another objective of the present invention is to provide a control system for a underground boring machine wherein the receiver is selectively positionable above the grade.
Another objective of the present invention is to provide a control system for a underground boring machine that provides feedback to automatically control the direction of the drillhead.
Another objective of the present invention is to provide a control system for a underground boring machine that automatically controls the horizontal and vertical direction of the drillhead without the need for drillhead adjustments to be made by an operator.
Another objective of the present invention is to provide a control system for a underground boring machine, the control system having a receiver that can be readily repositioned above grade to permit the desired path of the drillhead to be adjusted.
Another objective of the present invention is to provide a control system for a underground boring machine that can control the installation of a subterranean pipe around an obstacle.
These and other objectives and advantages are obtained by the improved control system for an auger drill directional control system of the present invention, the general nature of which may be stated as including a positional transmitter disposed at a drillhead, the positional transmitter being adapted to transmit a positional signal, a positional receiver disposed above the grade and selectively positioned above the desire terminal location of the drillhead, the positional receiver being adapted to receive the positional signal from the positional transmitter, control means for communicating with the positional receiver and creating a correction signal, and an adjustment apparatus in communication with the control means, the adjustment apparatus operationally connected to the drillhead, the adjustment apparatus adapted to adjust the direction of the drillhead in response to the correction signal.
Still other objectives and advantages are obtained by the improved method of the present invention, the general nature of which can be stated as including the steps of providing an underground boring machine, providing a positional transmitter mounted on at least a part of the underground boring machine, generating a positional signal with the positional transmitter, providing a positional receiver, placing the positional receiver above the grade at the desired terminus and in line with the direction of the drillhead, receiving the positional signal by the positional receiver, generating a correction command, and adjusting the underground boring machine in response to the correction command.